Hi Dan,
Welcome to the forum. Hope you enjoy your new D40.
Fitting a canopy is generally not a difficult task and shouldn't involve much in the way of hacking or modification, however I can understand your desire to fit it yourself. That way you can be sure of the alignment and fit. Take your time and you should be sweet.
As Krafy alluded to, make sure to have plenty of extra hands available for the lifting phase - they aren't light.